/*
 *
 * Copyright 2016 gRPC authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

#include <grpc/census.h>
#include <grpc/support/log.h>
#include <grpc/support/port_platform.h>
#include <grpc/support/useful.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include "src/core/ext/census/base_resources.h"
#include "src/core/ext/census/resource.h"
#include "test/core/util/test_config.h"

#include "src/core/ext/census/gen/trace_context.pb.h"
#include "src/core/ext/census/trace_context.h"
#include "third_party/nanopb/pb_decode.h"
#include "third_party/nanopb/pb_encode.h"

#define BUF_SIZE 256

/* Encodes a TraceContext structure (ctxt1) to a buffer, and then decodes it
to a second TraceContext (ctxt2).  Validates that the resulting TraceContext
has a span_id, trace_id, and that the values are equal to those in initial
TraceContext. On success, returns true.  If encode_trace_context returns 0,
decode_trace_context fails, or the resulting TraceContext is missing a trace_id
or span_id, it will return false. */
bool validate_encode_decode_context(google_trace_TraceContext *ctxt1,
                                    uint8_t *buffer, size_t buf_size) {
  google_trace_TraceContext ctxt2 = google_trace_TraceContext_init_zero;
  size_t msg_length;

  msg_length = encode_trace_context(ctxt1, buffer, buf_size);
  if (msg_length == 0) {
    return false;
  }

  if (!decode_trace_context(&ctxt2, buffer, msg_length)) {
    return false;
  }

  if (!ctxt2.has_trace_id_hi || !ctxt2.has_trace_id_lo || !ctxt2.has_span_id) {
    return false;
  }

  GPR_ASSERT(ctxt1->trace_id_hi == ctxt2.trace_id_hi &&
             ctxt1->trace_id_lo == ctxt2.trace_id_lo &&
             ctxt1->span_id == ctxt2.span_id &&
             ctxt1->has_span_options == ctxt2.has_span_options &&
             (ctxt1->has_span_options
                  ? ctxt1->span_options == ctxt2.span_options
                  : true));

  return true;
}

/* Decodes a proto-encoded TraceContext from a buffer.  If decode_trace_context
fails or the resulting TraceContext is missing a trace_id or span_id it will
return false, otherwise returns true. */
bool validate_decode_context(google_trace_TraceContext *ctxt, uint8_t *buffer,
                             size_t msg_length) {
  // Validate the decoding of a context written to buffer.
  if (!decode_trace_context(ctxt, buffer, msg_length)) {
    return false;
  }

  if (!ctxt->has_trace_id_hi || !ctxt->has_trace_id_lo || !ctxt->has_span_id) {
    return false;
  }

  return true;
}

/* Read an encoded trace context from a file.  Validates that the decoding
gives the expected result (succeed). */
static void read_and_validate_context_from_file(google_trace_TraceContext *ctxt,
                                                const char *file,
                                                const bool succeed) {
  uint8_t buffer[BUF_SIZE];
  FILE *input = fopen(file, "rb");
  GPR_ASSERT(input != NULL);
  size_t nbytes = fread(buffer, 1, BUF_SIZE, input);
  GPR_ASSERT(nbytes <= BUF_SIZE && feof(input) && !ferror(input));
  bool res = validate_decode_context(ctxt, buffer, nbytes);
  GPR_ASSERT(res == succeed);
  GPR_ASSERT(fclose(input) == 0);
}

// Test full proto-buffer.
static void test_full() {
  google_trace_TraceContext ctxt = google_trace_TraceContext_init_zero;
  read_and_validate_context_from_file(
      &ctxt, "test/core/census/data/context_full.pb", true);
}

// Test empty proto-buffer.
static void test_empty() {
  google_trace_TraceContext ctxt = google_trace_TraceContext_init_zero;
  read_and_validate_context_from_file(
      &ctxt, "test/core/census/data/context_empty.pb", false);
}

// Test proto-buffer with only trace_id.
static void test_trace_only() {
  google_trace_TraceContext ctxt = google_trace_TraceContext_init_zero;
  read_and_validate_context_from_file(
      &ctxt, "test/core/census/data/context_trace_only.pb", false);
}

// Test proto-buffer with only span_id.
static void test_span_only() {
  google_trace_TraceContext ctxt = google_trace_TraceContext_init_zero;
  read_and_validate_context_from_file(
      &ctxt, "test/core/census/data/context_span_only.pb", false);
}

// Test proto-buffer without span_options value.
static void test_no_span_options() {
  google_trace_TraceContext ctxt = google_trace_TraceContext_init_zero;
  read_and_validate_context_from_file(
      &ctxt, "test/core/census/data/context_no_span_options.pb", true);
  GPR_ASSERT(ctxt.has_span_options == false && ctxt.span_options == 0);
}

static void test_encode_decode() {
  uint8_t buffer[BUF_SIZE] = {0};

  google_trace_TraceContext ctxt1 = google_trace_TraceContext_init_zero;
  ctxt1.has_trace_id_hi = true;
  ctxt1.has_trace_id_lo = true;
  ctxt1.trace_id_lo = 1;
  ctxt1.trace_id_hi = 2;
  ctxt1.has_span_id = true;
  ctxt1.span_id = 3;
  validate_encode_decode_context(&ctxt1, buffer, sizeof(buffer));

  // Missing trace_id. This should fail.
  google_trace_TraceContext ctxt2 = google_trace_TraceContext_init_zero;
  ctxt2.has_trace_id_hi = false;
  ctxt2.has_trace_id_lo = false;
  ctxt2.has_span_id = true;
  validate_encode_decode_context(&ctxt2, buffer, sizeof(buffer));
}

// Test a corrupted proto-buffer. This should fail.
static void test_corrupt() {
  uint8_t buffer[BUF_SIZE] = {0};
  google_trace_TraceContext ctxt1 = google_trace_TraceContext_init_zero;
  size_t msg_length;

  ctxt1.has_trace_id_hi = true;
  ctxt1.has_trace_id_lo = true;
  ctxt1.trace_id_lo = 1;
  ctxt1.trace_id_hi = 2;
  ctxt1.has_span_id = true;
  ctxt1.span_id = 3;
  ctxt1.has_span_options = true;
  ctxt1.span_options = SPAN_OPTIONS_IS_SAMPLED;
  msg_length = encode_trace_context(&ctxt1, buffer, sizeof(buffer));

  /* Corrupt some bytes.  255 (0xFF) should be illegal for the first byte of the
  proto encoded object. */
  buffer[0] = 255;

  bool res = validate_decode_context(&ctxt1, buffer, msg_length);
  GPR_ASSERT(res == false);
}

static void test_buffer_size() {
  // This buffer is too small. This should fail.
  uint8_t buffer[16] = {0};
  google_trace_TraceContext ctxt1 = google_trace_TraceContext_init_zero;
  size_t msg_length;

  ctxt1.has_trace_id_hi = true;
  ctxt1.has_trace_id_lo = true;
  ctxt1.trace_id_lo = 1;
  ctxt1.trace_id_hi = 2;
  ctxt1.has_span_id = true;
  ctxt1.span_id = 3;
  ctxt1.has_span_options = true;
  ctxt1.span_options = SPAN_OPTIONS_IS_SAMPLED;
  msg_length = encode_trace_context(&ctxt1, buffer, sizeof(buffer));

  GPR_ASSERT(msg_length == 0);
}

int main(int argc, char **argv) {
  grpc_test_init(argc, argv);
  test_full();
  test_empty();
  test_trace_only();
  test_span_only();
  test_encode_decode();
  test_corrupt();
  test_no_span_options();
  test_buffer_size();

  return 0;
}